Coupled and synchronous mirror elements in a lidar-based micro-mirror array

ABSTRACT

Some embodiments include a MEMS apparatus configured to redirect light in a LiDAR system and includes a support frame and a plurality of mirror elements disposed in a linear array within the support frame including a first mirror element and a second mirror element. Each of the plurality of mirror elements can be rotatable on a rotational axis that is perpendicular to a line defined by the linear array of the plurality of mirror elements and bisects the corresponding mirror element into a first portion and a second portion. The apparatus can include a coupling element having a distal end physically coupled to a first portion of the first mirror element and a proximal end physically coupled to a second portion of the second mirror element such that a rotation of the first mirror element causes a synchronous and equal rotation of the second mirror element.

CROSS-REFERENCES TO RELATED APPLICATIONS

The following eight U.S. patent applications listed below (whichincludes the present application) are being filed concurrently, and theentire disclosures of the other applications are incorporated byreference into this application for all purposes:

application Ser. No. ______, filed Dec. 7, 2018, entitled“MULTI-THRESHOLD LIDAR DETECTION” (Attorney Docket No.103343-1103454-000400US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “MIRRORASSEMBLY FOR LIGHT STEERING” (Attorney Docket No.103343-1103456-000500US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “COUPLED ANDSYNCHRONOUS MIRROR ELEMENTS IN A LIDAR-BASED MICRO-MIRROR ARRAY”(Attorney Docket No. 103343-1103457-000600US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “COUPLED ANDSYNCHRONOUS MIRROR ELEMENTS IN A LIDAR-BASED MICRO-MIRROR ARRAY”(Attorney Docket No. 103343-1117781-000610US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “NON-LINEARSPRINGS TO UNIFY THE DYNAMIC MOTION OF INDIVIDUAL ELEMENTS IN AMICRO-MIRROR ARRAY” (Attorney Docket No. 103343-1103460-000700US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “NON-LINEARSPRINGS TO UNIFY THE DYNAMIC MOTION OF INDIVIDUAL ELEMENTS IN AMICRO-MIRROR ARRAY” (Attorney Docket No. 103343-1117776-000710US);

application Ser. No. ______, filed Dec. 7, 2018, entitled “A LEVERSYSTEM FOR DRIVING MIRRORS OF A LIDAR TRANSMITTER” (Attorney Docket No.103343-1103464-000800US); and

application Ser. No. ______, filed Dec. 7, 2018, entitled “SYSTEM ANDMETHODS FOR CONTROLLING MICRO-MIRROR ARRAY” (Attorney Docket No.103343-1103466-000900US).

BACKGROUND

Modern vehicles are often fitted with a suite of environment detectionsensors that are designed to detect objects and landscape featuresaround the vehicle in real-time that can be used as a foundation formany present and emerging technologies such as lane change assistance,collision avoidance, and autonomous driving capabilities. Some commonlyused sensing systems include optical sensors (e.g., infra-red, cameras,etc.), radio detection and ranging (RADAR) for detecting presence,direction, distance, and speeds of other vehicles or objects,magnetometers (e.g., passive sensing of large ferrous objects, such astrucks, cars, or rail cars), and light detection and ranging (LiDAR).

LiDAR typically uses a pulsed light source and detection system toestimate distances to environmental features (e.g., vehicles,structures, etc.). In some systems, a laser or burst of light (pulse) isemitted and focused through a lens assembly and a reflection of thepulse off of an object is collected by a receiver. A time-of-flight(TOF) of the pulse can be measured from the time of emission to the timethe reflection is received, which may manifest as a single data point.This process can be repeated very rapidly over any desired range, whichmay typically be over an area in front of the vehicle, or over a 360degree radius. The TOF measurements can be captured to form a collectionof points that are dynamically and continuously updated in real-time,forming a “point cloud.” The point cloud data can be used to estimate,for example, a distance, dimension, and location of the object relativeto the LiDAR system, often with very high fidelity (e.g., within 5 cm),that can be used to map an area around the vehicle such that the vehicleis spatially aware of its surroundings and can, for example, alert adriver to obstacles, hazards, or points of interest, or take acorrective action (e.g., apply brakes) in the event of a possiblecollision.

Despite the promise that LiDAR and other sensing systems bring to thecontinued development of fully autonomous transportation, there arechallenges that limit its widespread adoption. LiDAR systems are oftenexpensive, large, and bulky. In some cases, multiple emitters may beneeded to accurate track a scene, particularly for systems that requireaccuracy over a large range and field-of-view (FOV). While significantstrides have been made to push autonomous vehicle technology to greatercommercial adoption, more improvements are needed.

BRIEF SUMMARY

This summary is not intended to identify key or essential features ofthe claimed subject matter, nor is it intended to be used in isolationto determine the scope of the claimed subject matter. The subject mattershould be understood by reference to appropriate portions of the entirespecification of this disclosure, any or all drawings, and each claim.

The foregoing, together with other features and examples, will bedescribed in more detail below in the following detailed description,claims, and accompanying drawings.

In some embodiments, a micro-electro-mechanical system (MEMS) apparatusconfigured to redirect light in a light detection and ranging (LiDAR)system can include a support frame; a plurality of mirror elementsdisposed in a linear array in an end-to-end, longitudinally configuredarrangement within the support frame, the plurality of mirror elementsincluding: a first mirror element; and a second mirror element, thesecond mirror element adjacent to and linearly aligned with the firstmirror element. Each mirror element of the plurality of mirror elementsmay be rotatable on a rotational axis that is perpendicular to a linedefined by the linear array of the plurality of mirror elements, therotational axis of each mirror element bisecting the correspondingmirror element into a first portion and a second portion. The MEMSapparatus can further include a coupling element having a distal endcoupled to a first portion of the first mirror element and a proximalend coupled to a second portion of the second mirror element, wherebythe coupling element physically couples the first and second mirrorelements such that a rotation of the first mirror element causes asynchronous and equal rotation of the second mirror element, and arotation of the second mirror element causes a synchronous and equalrotation of the first mirror element.

In certain embodiments, each mirror element can include a first couplinglocation on its first portion and a second coupling location on itssecond portion, the first coupling location and second coupling locationdefining where the coupling element is configured to couple to, wherethe first coupling location and the second coupling location areequidistant from and on opposite sides of a rotational axis of thecorresponding mirror element. The MEMS apparatus can further include oneor more processors; and one or more MEMS motors controlled by the one ormore processors and configured to rotate at least one of the firstmirror element and second mirror element, where the coupling elementcauses the plurality of mirror elements to synchronously, mechanically,and equally rotate over a range of motion as the one or more MEMS motorsrotates the at least one of the first mirror element and second mirrorelement. The range of motion can include any suitable rotational range(e.g., within 90 degrees). In some cases, the support frame, theplurality of mirror elements, and the coupling element together can forma continuous, unitary structure formed on a common substrate (e.g.,etched on a same plane of a semiconductor substrate). In furtherembodiments, the MEMS apparatus can also include a third mirror element(or more), the third mirror element adjacent to and linearly alignedwith the second mirror element; and a second coupling element having adistal end coupled to a first portion of the second mirror element and aproximal end coupled to a second portion of the third mirror element,whereby the coupling element physically couples the second and thirdmirror elements such that a rotation of the third mirror element causesa synchronous and equal rotation of the first and second mirrorelements.

The first portion of the first mirror element and the second portion ofthe second mirror can both include a longitudinally-oriented channelthat is configured to allow the coupling element to pass through a planedefined by the first mirror element and the second mirror element as thefirst and second mirror elements are rotated. In some cases, thecoupling element may be flexible and may flex as the first and secondmirror elements are rotated. The support frame can include a couplingelement support configured parallel to the rotational axes of the firstand second mirror elements and between the first and second mirrorelements, where the coupling element pivots on the coupling elementsupport as the first and second mirror elements are rotated. The firstmirror element may be coupled to the support frame by at least onesupport hinge (typically two linearly aligned hinges) configured alongthe rotational axis and facilitates the rotation of the first and secondmirror elements along the rotational axis. In some cases, the at leastone support hinge, the support frame, the first and second mirrorelements, and the coupling element are a continuous, unitary structure,and may be formed (e.g., etched via photolithography or othersemiconductor fabrication processes, etc.) on a common substrate. Eachof the plurality of mirror elements may be of the same size anddimensions. For instance, some embodiments may be configured such thateach of the plurality of mirror elements are rectangular with twoopposing ends separated by a first distance defining a length andlongitudinal arrangement of the corresponding mirror element, and twoopposing sides separated by a second distance defining a width of thecorresponding mirror element. In some implementations, the support framecan include a support structure that is configured perpendicular to thelinear array and at a location between the first and second mirrors,where the support structure supports the coupling element at a pivotpoint, and where the coupling element rotates at the pivot point.

In certain embodiments, a MEMS apparatus configured to redirect light ina LiDAR system may include a support frame; a first mirror elementcoupled to the support frame by a first support hinge, wherein the firstmirror element is rotatable relative to the support frame along arotational axis at the first support hinge and defined by an orientationof the first support hinge; a second mirror element coupled to thesupport frame by a second support hinge, wherein the second mirrorelement is rotatable relative to the support frame along a rotationalaxis at the second support hinge and defined by an orientation of thesecond support hinge; and a coupling element coupling the first mirrorelement to the second mirror element such that a rotation of the firstmirror element causes the second mirror element to rotate synchronouslyand equally with the first mirror element, and a rotation of the secondmirror element causes the first mirror element to rotate synchronouslyand equally with the second mirror element. The first and second mirrorelements may be disposed in a linear array in an end-to-end,longitudinally configured arrangement within the support frame.Typically, the array is more than two mirror elements, as shown in FIGS.5B-5D and 7B-7D. In some cases, the first and second mirror elements canhave a rotation range of 90 degrees (typically within 45-90 degrees),however other ranges are possible. The support frame, the first andsecond mirror elements, and the coupling element together may form acontinuous, unitary structure formed on a common substrate. In somecases, the coupling element may flex as the first and second mirrorelements are rotated. Further, the support frame can include a couplingelement support configured parallel to the rotational axes of the firstand second mirror elements and between the first and second mirrorelements, and wherein the coupling element pivots on the couplingelement support as the first and second mirror elements are rotated.

In certain embodiments, a MEMS apparatus configured to redirect light ina LiDAR system can include a support frame; a plurality of mirrorelements disposed in a linear array in an end-to-end, longitudinallyconfigured arrangement within the support frame, wherein each mirrorelement of the plurality of mirror elements is rotatable on a rotationalaxis that is perpendicular to a line defined by the linear array of theplurality of mirror elements; and a coupling element configured adjacentto and in parallel with the linear array of the plurality of mirrorelements, the coupling element coupled to substantially a same locationat each of the plurality of mirror elements, whereby the couplingelement physically couples each of the plurality of mirror elementstogether such that a rotation of any one of the plurality of mirrorelements causes a synchronous and equal rotation of the remaining mirrorelements of the plurality of mirror elements coupled to the couplingelement. The MEMS apparatus may further include one or more processors;and one or more MEMS motors or actuators controlled by the one or moreprocessors and configured to drive the coupling element that causes theplurality of mirror elements to synchronously and equally rotate over arange of motion. The range of motion, au include a rotational range ofwithin 90 degrees (e.g., 45-90 degrees), although other ranges arepossible. The support frame, the coupling element, and the plurality ofmirror elements may be formed as a continuous, unitary structure with acommon substrate. In some cases, the common substrate can be asemiconductor substrate and the support frame, the coupling element, andthe plurality of mirror elements may be on a common plane.

Each of the plurality of mirror elements can be of the same size anddimensions, although other arrangements are possible. The first mirrorelement can be coupled to the support frame by at least one supporthinge configured along the rotational axis and facilitates the rotationof the first and second mirror elements along the rotational axis. Insome embodiments, the at least one support hinge, the support frame, thefirst and second mirror elements, and the coupling element can be acommon, unitary structure formed on a common substrate. Each of theplurality of mirror elements can be rectangular with two opposing endsseparated by a first distance defining a length and longitudinalarrangement of the corresponding mirror element; and two opposing sidesseparated by a second distance defining a width of the correspondingmirror element. Other shapes of mirror elements are possible, as wouldbe appreciated by one of ordinary skill in the art with the benefit ofthis disclosure. The coupling elements may flex as the first and secondmirror elements are rotated.

In further embodiments, a MEMS apparatus configured to redirect light ina LiDAR system may include a support frame; a plurality of mirrorelements disposed in a linear array within the support frame, whereineach mirror element of the plurality of mirror elements is rotatable ona rotational axis that is perpendicular to a line defined by the lineararray of the plurality of mirror elements; and a coupling elementcoupled to substantially a same location at each of the plurality ofmirror elements, whereby the coupling element physically couples each ofthe plurality of mirror elements together such that a rotation of anyone of the plurality of mirror elements causes a synchronous and equalrotation of the remaining mirror elements of the plurality of mirrorelements coupled to the coupling element. The MEMS apparatus may includeone or more processors; and one or more MEMS motors or actuatorscontrolled by the one or more processors and configured to drive thecoupling element that causes the plurality of mirror elements tosynchronously and equally rotate over a range of motion. The range ofmotion can include a rotational range of within 90 degrees (e.g., 45-90degrees, or other suitable range). The support frame and the pluralityof mirror elements can be formed on a common substrate and each of theplurality of mirror elements may be of the same size and dimensions. Forexample, some embodiments may be configured such that each of theplurality of mirror elements are rectangular with two opposing endsseparated by a first distance defining a length and longitudinalarrangement of the corresponding mirror element; and two opposing sidesseparated by a second distance defining a width of the correspondingmirror element. The first mirror element can be coupled to the supportframe by at least one support hinge (typically two support hinges, asshown in FIGS. 7A-7D) configured along the rotational axis thatfacilitates the rotation of the first and second mirror elements alongthe rotational axis. In some cases, the at least one support hinge, thesupport frame, the first and second mirror elements, and the couplingelement are a unitary structure that may be formed on a commonsubstrate. In some cases, these structures may be formed on a commonplane.

In certain embodiments, a MEMS apparatus configured to redirect light ina LiDAR system may include a support frame; a plurality of mirrorelements disposed in a linear array within the support frame, whereineach mirror element of the plurality of mirror elements is rotatable ona rotational axis that is perpendicular to a line defined by the lineararray of the plurality of mirror elements; at least one support hingefor each of the plurality of mirror elements, each support hingeconfigured along the rotational axis and configured to couple acorresponding mirror element to the support frame, each support hingeconfigured to facilitate the rotation of the first and second mirrorelements along the rotational axis; and a flexible coupling elementcoupled to substantially a same location at each of the plurality ofmirror elements, whereby the coupling element physically couples each ofthe plurality of mirror elements together such that a rotation of anyone of the plurality of mirror elements causes a synchronous and equalrotation of the remaining mirror elements of the plurality of mirrorelements coupled to the coupling element. In some embodiments, the atleast one support hinge, the support frame, the first and second mirrorelements, and the coupling element can be a unitary structure formed ona common substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures.

FIG. 1 shows an autonomous driving vehicle using a LiDAR-based system,according to certain embodiments.

FIG. 2 shows an example of a light steering using a LiDAR based system,according to certain embodiments.

FIG. 3 shows an example of a MEMS-based micro-mirror assembly in aLiDAR-based system, according to certain embodiments.

FIG. 4 shows an example of an operation of the micro-mirror assembly ofFIG. 3 to provide a two-dimensional field of view (FOV), according tocertain embodiments.

FIG. 5A-FIG. 5F show a first type of coupled, synchronous linear arrayof micro-mirrors operating over a range of motion, according to certainembodiments.

FIGS. 6A-6B show simplified functional diagrams of the coupled,synchronous linear array of micro-mirrors shown in FIGS. 5A-5F,according to certain embodiments.

FIGS. 7A-7E show a second type of coupled, synchronous linear array ofmicro-mirrors operating over a range of motion, according to certainembodiments.

FIGS. 8A-8B show simplified functional diagrams of the coupled,synchronous linear array of micro-mirrors shown in FIGS. 7A-7E,according to certain embodiments.

DETAILED DESCRIPTION

Aspects of the present disclosure relate generally to object trackingsystems, and more particularly to MEMS-based, synchronous micro-mirrorarray systems configured for light steering in a LiDAR system.

In the following description, various examples of MEMS-based,synchronous micro-mirror array systems are shown and described. Forpurposes of explanation, specific configurations and details are setforth in order to provide a thorough understanding of the embodiments.However, it will be apparent to one skilled in the art that certainembodiments may be practiced or implemented without every detaildisclosed. Furthermore, well-known features may be omitted or simplifiedin order to prevent any obfuscation of the novel features describedherein.

The following provides a general non-limiting overview of the disclosurethat follows. A LiDAR system typically uses a pulsed light source thatis focused through a lens assembly to transmit and receive pulsesreflected off of an object, with each detected return pulse captured asa single data point. An example of a LiDAR system on an autonomousvehicle is shown in FIG. 1, and is further described below. A TOF foreach detected measurement can be captured to form a collection of pointsthat are dynamically and continuously updated in real-time, forming a“point cloud.” The point cloud data can be used to estimate, forexample, a distance, dimension, and location of the object relative tothe LiDAR system. In order to transmit and detect pulses in two or moredimensions, a light deflecting or “light steering” system (see, e.g.,FIG. 2) can be used to both deflect the transmit and receive pulses overa range to generate a larger field of view for object detection. In somesystems, a light steering apparatus may include a movable mirrorassembly to allow configurability in the direction of light projection.A mirror in the mirror assembly can be moved (e.g., rotated/tilted) byactuators (controlling coupling elements, as described below) to reflect(and steer) light from a light source towards a pre-configured angle.The mirror can be rotated to provide a first range of angles ofprojection along a first (e.g., vertical) axis for a one-dimensional(1D) field-of-view and, in some implementations, a second range ofangles of projection along a second (e.g., horizontal) axis, which canbe orthogonal to the first axis. The first range and the second range ofangles of projection can define a 1D or 2D field-of-view that an objectcan be detected. The mirror assembly can have a material effect onvarious performance metrics of the light steering apparatus includingprecision, actuation power, FOV, dispersion angle, reliability,resolution, ranging, and imaging properties. In some embodiments,certain features of the light steering system, including the mirrorassembly, actuators, and the control circuitries that configure theactuators to set the angles of projection, can be formed asmicroelectromechanical systems (MEMS) on a semiconductor substrate.

In some cases, the optical aperture of the system may be determined bythe mirror size. A larger optical aperture is often preferred in mostapplications, which can be achieved through increasing mirror sizes.However, this can sacrifice other performances, such as the speed thatthe mirrors are operating at. For example, systems using a single mirrorto provide light steering (e.g., in a single axis) would require arelatively high actuation force to achieve a target FOV and a targetdispersion, which can reduce reliability. Furthermore, to reducedispersion, the size of the mirror can be made to match the width of thelight pulses (e.g., light columns) from the light source, which can leadto an increased mass and inertia of the mirror. As a result, a largeractuation force (e.g., torque) may be needed to rotate the mirror toachieve the target FOV. Subjecting MEMS actuators to large activationforces can require significantly power resources and can shorten thelifespan and reduce the reliability of the actuators. In some cases, itmay not be possible to move the mirror at a desired rate and range infast scanning scenarios using MEMS actuators due to the mass andinertial characteristics of the large mirror(s).

A solution to this problem, as presented herein, is to use a MEMS-basedmirror arrays (see, e.g., FIG. 3) to replace the large mirror apparatus.In such cases, the size and mass of the individual mirrors can besignificantly smaller and lighter so that a higher scanning speed (usingless power) can be achieved. Individually, a smaller mirror size cansignificantly reduce the capability to deliver and receive light (e.g.,LiDAR) pulses since less mirror surface area is available for lightreflection. In contrast, an array of smaller MEMS micro-mirrors can beconfigured in any suitable dimension to effectively achieve a largermirrored area of reflection (e.g., which may be comparable to the singlelarge mirror or larger), but with the myriad benefits including fasterindividual mirror tilt control and at a reduced power consumption.

In order for an array of mirrors to operate collectively as a similarlysized single mirror, each individual mirror in the array needs to besynchronized so that at any point in time all of the mirrors in thearray are oriented (also referred to as tilted) toward the samedirection. Otherwise, light pulses striking the array of micro-mirrorsmay be dispersed in multiple directions, resulting in poor performance(e.g., tracking) characteristics, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure. In anideal MEMS-based system where every mirror in the array is identicallyfabricated, a synchronized movement of each mirror of the array (e.g.,via actuators coupled to each mirror) could theoretically be achieved aslong as the driving signal applied to each mirror is identical. However,due to variations in the manufacturing and fabrication process, themirrors may have slightly different masses and/or dimensions, such thatan identical driving signal applied to each mirror can result inslightly different responses and, for example, poor uniformity of thereflection across the array and corresponding poor dispersionproperties.

Aspects of the invention are directed to solving the problem ofsynchronizing a movement (e.g., rotation) and orientation (tilt) of anarray of mirrors in a MEMS-based micro-mirror array particularly wherethere may be micro-variations in mass and/or dimensions between eachmirror of the array. Some of the techniques presented herein involve amechanical coupling between mirrors to synchronize movement across themirror array. In some embodiments, a multi-lever mechanical couplingmechanism (using multiple coupling elements) can be used to synchronizemovement across an array of micro-mirrors, as shown and described belowwith respect to FIGS. 5A-6B. In further embodiments, a lever with acommon mechanical connection (a coupling element) at each mirror can beused to mechanically synchronize mirror movement and orientation acrossthe array, as shown and described below with respect to FIGS. 7A-8B.Although linear arrays and single axis embodiments are presented herein,it should be understood that two-dimensional arrays of mirrors usingmultiple couple elements can be used for two-dimensional movement and/ormulti-array control, as further discussed below.

Typical System Environment for Certain Embodiments

FIG. 1 shows a vehicle 100 utilizing a LiDAR-based detection system,according to certain embodiments. Vehicle 100 can include a LiDAR module102. LiDAR module 102 can enable vehicle 100 to perform object detectionand ranging in a surrounding environment. Based on the result of objectdetection and ranging, vehicle 100 can, for example, maneuver to avoid acollision with the object. LiDAR module 102 can include light steeringmodule 104 and a receiver 106. Light steering module 104 can beconfigured to project one or more light pulses 108 at various directionsat different times in any suitable scanning pattern, while receiver 106can monitor for a return light pulse 110 which is generated by thereflection of light pulse 108 by an object 112. LiDAR module 102 candetect the object based on the reception of light pulse 110, and canperform a ranging determination (e.g., a distance of the object) basedon a time difference between light pulses 108 and 110, which may bereferred to as a time-of-flight (TOF). As indicated above, thisoperation can be repeated very rapidly over any desired range. In somecases, scanning (e.g., pulse emission and detection) may be performedover 360 degrees over a two-dimensional (2D) plane for ground-basedvehicles (as vehicle detection systems may be primarily concerned withobjects and environmental features on the ground), or over a threedimensional (3D) volumetric area.

In some embodiments, a spinning mirror system (e.g., LiDAR module 102)may be used that can allow a single laser to aim over 360 degrees at ahigh rate of rotation (e.g., 500-5000 RPMs or more) over a single planeto form a collection of points (e.g., each point being an individualmeasurement such as one sent and reflected pulse) that are dynamicallyand continuously updated in real-time, forming a “point cloud.” Thepoint cloud data can be used to estimate, for example, a distance,dimension, and location of the object relative to the LiDAR system,often with a very high fidelity (e.g., within 2 cm). In some cases, athird dimension (e.g., height) may be performed in a number of differentmanners. For example, the spinning mirror system (or other suitableapparatus) can be moved up and down (e.g., on a gimbal or otheractuating device) to increase the field of view (FOV) of the scan.Although not shown or discussed further, it should be understood thatother LiDAR systems may be used to develop a point cloud and mayincorporate the novel aspects of the various threshold-adjusteddetection schemes described herein. For example, some scanningimplementations may employ solid state, flash-based LiDAR units that canbe configured to scan a 2D focal plane area. One of ordinary skill inthe art with the benefit of this disclosure would appreciate the manyalternative embodiments and modifications thereof.

Referring back to FIG. 1, LiDAR module 102 can transmit light pulse 110(send signal) at a direction directly in front of vehicle 100 at time T1and receive light pulse 110 (return signal) reflected by an object 112(e.g., another vehicle) at time T2. Based on the reception of lightpulse 110, LiDAR module 102 can determine that object 112 is directly infront of vehicle 100. Moreover, based on the time difference between T1and T2, LiDAR module 102 can also determine a distance 114 betweenvehicle 100 and object 112, and may glean other useful information withadditional received pulses including a relative speed and/oracceleration between the vehicles and/or dimensions of the vehicle orobject (e.g., the width of the object in 2D, or a height and width (orportion thereof depending on the FOV) with 3D detection. Thus, vehicle100 can adjust its speed (e.g., slowing or stopping) to avoid collisionwith object 112, or modulate systems such as adaptive cruise control,emergency brake assist, anti-lock braking systems, or the like, based onthe detection and ranging of object 112 by LiDAR module 102.

FIG. 2 illustrates an example of internal components of a LiDAR module102. LiDAR module 102 may include a light steering transmitter 202, areceiver 204, and a LiDAR controller 206, which can control theoperations of light steering transmitter 202 and receiver 204. Lightsteering transmitter 202 can include a pulsed light source 208, acollimator lens 210, and a mirror assembly 212, whereas receiver 204 caninclude a lens 214 and a photodetector 216. LiDAR controller 206 cancontrol pulsed light source 208, which can include a pulsed laser diode,to transmit light pulse 108, which is part of pulsed light 218. Pulsedlight 218 can disperse upon leaving pulsed light source 208 and can beconverted into collimated/parallel pulsed light 218 by collimator lens210. Collimator lens 210 can have an aperture length 220, which can seta width of collimated pulsed light 218.

Collimated pulsed light 218 can be incident upon mirror assembly 212,which can reflect collimated pulsed light 218 to steer it along a outputprojection path 219 towards object 112. Mirror assembly 212 can includeone or more rotatable mirrors. FIG. 2 shows mirror assembly 212 ashaving one mirror, but as described below, certain embodiments include amirror assembly 212 with a plurality of mirrors configured in one ormore arrays, as shown and described with respect to FIGS. 3-8. Referringback to FIG. 2, in order to reduce the dispersion of collimated pulsedlight 218 along output projection path 219, the one or more rotatablemirrors can have a length (or width) that matches aperture length 220,which can set the width of collimated bundle of pulsed light 218. Sucharrangement enables mirror assembly 212 to reflect and project a largerportion of collimated bundle of pulsed light 218 towards the far fieldto mitigate the dispersion effect experienced by the reflected light enroute to the far field.

Mirror assembly 212 further can include one or more coupling elements(not shown in FIG. 2) to mechanically rotate the rotatable mirrors in asynchronized fashion along a first axis 222 and, in some cases, a secondaxis 226. The coupling elements can be controlled by one or more MEMSactuators (not shown in FIG. 2). As further described below, therotation around first axis 222 can change a first angle 224 of outputprojection path 219 with respect to a first dimension (e.g., thex-axis), whereas the rotation around second axis 226 can change a secondangle 228 of output projection path 219 with respect to a seconddimension (e.g., the z-axis). LiDAR controller 206 can control theactuators to produce different combinations of angle of rotations aroundfirst axis 222 and second axis 226 such that the movement of outputprojection path 219 can follow a scanning pattern 232. A range 234 ofmovement of output projection path 219 along the x-axis, as well as arange 238 of movement of output projection path 219 along the z-axis,can define a FOV. An object within the FOV, such as object 112, canreceive and reflect collimated pulsed light 218 to form reflected pulseto form light pulse 110, which can be received by receiver 204.

MEMS-Based Micro-Mirror Arrays

In the embodiments that follow, a number of micro-electro-mechanicalsystems (MEMS) are presented that include micro-mirror array structuresthat can be integrated with the LiDAR systems described above. MEMS canbe described as a miniature mechanical and electro-mechanical elements(e.g., sub-micron to mm dimensions) that can be formed into variousdevices and structures using microfabrication techniques. MEMS devicescan vary in complexity from simple static structures with no movingelements, to highly complex electromechanical systems with movingelements that can be controlled by integrated microelectronics. Some ofthe moving, functional elements can include transducers such asmicro-sensors and micro-actuators. In aspects of the present invention,micro-actuators may be used to actuate the coupling elements thatmechanically couple and synchronize the micro-mirrors in an array, asfurther described below at least with respect to FIGS. 5A-8. In someembodiments, the MEMS micro-mirror arrays described herein can beintegrated on a common silicon substrate, along with integrated circuits(e.g., microelectronics) that can include circuitry to control themicro-mirror array. Some typical fabrication processes can includecomplimentary metal-oxide semiconductor (CMOS) processes, Bipolarprocesses, Bipolar CMOS (BICMOS) processes, or the like. While singlesubstrate embodiments are shown and described herein, it should beunderstood that multi-substrate systems (e.g., mirror arrays ondifferent substrates) are possible, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure.

Compared with an arrangement where a light steering transmitter uses asingle mirror having two axes of rotation to provide two ranges ofprojection angles to form a FOV (e.g., as shown in FIG. 2), someembodiments can use a first rotatable mirror and a second rotatablemirror (or an array of first rotatable mirrors and a second rotatablemirror) each having a single but orthogonal rotational axis to providethe two ranges of projection angles to form the FOV. Such arrangementscan improve reliability and precision and can reduce actuation power,while providing the same or superior FOV and dispersion.

FIGS. 3-4 show an example of a mirror assembly 300, according to certainembodiments. Mirror assembly 300 can be part of light steeringtransmitter 202. FIG. 3 shows a top view of mirror assembly 300 and FIG.4 shows a perspective view of mirror assembly 300. Mirror assembly 300can include an array of first rotatable mirrors 302(a), a secondrotatable mirror 304, and a stationary mirror 306. The array of firstrotatable mirrors 302(a) and second rotatable mirror 304 can be MEMSdevices implemented on a surface 308 of a semiconductor substrate 310.Stationary mirror 306 can be positioned above semiconductor substrate310. Referring to FIG. 4, in some configurations, array of firstrotatable mirrors 302(a) can receive collimated pulsed light 218 fromcollimator lens 210, reflect pulsed light 218 towards stationary mirror306, which can reflect pulsed light 218 towards second rotatable mirror304. Second rotatable mirror 304 can reflect pulsed light 218 receivedfrom stationary mirror 306 as an output along output projection path 219(represented by dotted line that is co-linear with reflected lightpulsed light 218). To illustrate how the pulsed light can be deflected,mirrors 302(b) show mirrors 302(a) in a rotated state. In such case,first rotatable mirrors 302(b) can receive collimated pulsed light 221from collimator lens 210, reflect pulsed light 221 towards stationarymirror 306, which can reflect pulsed light 221 towards second rotatablemirror 304. Second rotatable mirror 304 can reflect pulsed light 221received from stationary mirror 306 as an output along output projectionpath 222, which may not be co-linear with pulsed light 221, as would beappreciated by one of ordinary skill in the art with the benefit of thisdisclosure. In another configuration (not shown in the figures), secondrotatable mirror 304 can receive collimated pulsed light 218 fromcollimator lens 210 and reflect pulsed light 218 towards stationarymirror 306, which can reflect pulsed light 218 towards array of firstrotatable mirrors 302(a). Array of first rotatable mirrors 302(a) canreflect pulsed light 218 as an output along output projection path 219.As to be describe in details below, array of first rotatable mirrors302(a) and second rotatable mirror 304 change an angle of outputprojection path 219 with respect to, respectively, the x-axis and thez-axis, to form a two-dimensional FOV.

In some embodiments, each mirror of the array of first rotatable mirrors302(a) (e.g., first rotatable mirror 302(a)) can be rotatable around afirst axis 314, whereas second rotatable mirror 304 can be rotatablearound a second axis 316 which is orthogonal to first axis 314. Eachmirror of the array of first rotatable mirrors 302(a), as well as secondrotatable mirror 304, can be coupled with a pair of rotary actuators,such as comb drives, to rotate the mirror. For example, first rotatablemirror 302(a) is coupled with and rotary actuators 322 a and 322 b,whereas second rotatable mirror 304 is coupled with rotary actuators 324a and 324 b. Each of first rotatable mirror 302(a) (and the rest ofarray of first rotatable mirrors 302(a)) and second rotatable mirror 304can independently move output projection path 219 along, respectively,the x-axis and the z-axis, to form a FOV. In some embodiments, couplingelements may be used to mechanically couple each mirror in an arraytogether. For instance, adjacent mirrors in an array may be mechanicallycoupled together along the entire array, as shown in FIG. 5, or theentire array (or portion thereof) can be coupled together via a singlecoupling element, as shown in FIG. 7. In some cases, the rotaryactuators 324 a, 324 b, may rotate the mirrors along an axis in asynchronized fashion, and the coupling elements may further mechanicallysynchronize the movement of the array of mirrors, which can improve theaccuracy and synchronization since moving each mirror in the array viathe actuators alone may be subject to small variations due tofabrication tolerances and the like, as described above. Alternatively,the coupling elements as described below with respect to FIGS. 5A-8 maysolely control the rotation of the micro-mirror elements in an array inlieu of the rotary actuators. Although not shown in FIGS. 3 and 4, thecoupling elements described below would be generally configuredperpendicular to the axis 314, 316 in the corresponding mirror array, asfurther described below.

Compared with a single mirror assembly, mirror assembly 300 can providesimilar or superior FOV and dispersion performance while reducing theactuation force and power and improving reliability. First, each mirrorof the array of first rotatable mirrors 302(a), as well as the secondrotatable mirror 304, can be substantially smaller than a single mirrorhaving a comparable length and width and dispersion performance. As aresult, each mirror of mirror assembly 300 may use substantially lesstorque to provide the same FOV as the single mirror assembly. The torquecan be further reduced by independently optimizing the control signalsresponsible for each dimension of the FOV. For example, second rotatablemirror 304 of mirror assembly 300 can be driven at close to a naturalfrequency to induce harmonic resonance, which can substantially reduce arequired torque to achieve a target FOV. The reduction of torque alsoreduces the burden on the rotatory actuators and corresponding couplingelements, and can increase their operational lifespan and reducewear-and-tear. In addition, as a plurality of mirrors are involved inthe steering of light, the likelihood of any of the mirror becoming asingle source of failure can be mitigated, which can further improvereliability. The novel embodiments described herein (e.g., as presentedin FIGS. 5A-8B) may be applied to any LiDAR system presented in thefamily of cases that are incorporated by reference.

Synchronizing MEMS Micro-Mirror Arrays Using Mechanical CouplingElements

FIGS. 5A-5F show a first type of coupled, synchronous linear array ofmicro-mirrors 500 in a MEMS system, according to certain embodiments.Micro-mirror array 500 can be integrated in a larger MEMS structure,such as in the mirror assembly 300 of FIG. 3, in which case micro-mirrorarray 500 can correspond to array 302. As described above, conventionalmicro-mirror array structures in MEMS architectures are oftenindividually controlled by one or more actuators. Synchronizing theorientation of each mirror in the array can be problematic when thereare variations in the fabrication process (e.g., semi-conductor processtolerances) that may result in slightly mismatched micro mirror massand/or dimensions, variation in actuator performance (e.g., identicalvoltages on different actuators may yield slightly differentperformance), or the like. Such variations can ultimately manifest asnon-uniformly aligned (i.e., unsynchronized) mirrors, which can resultin degraded performance characteristics including poor signal dispersionand/or collecting light from different sources, rather than from asingle location (which can be desirable for object detection).

In the following MEMS micro-mirror arrays, actuators configured on themirror axes (e.g., like actuators 322 a and 322 b) are not shown indetail, but their locations are shown and their operation in the contextprovided would be appreciated by one of ordinary skill in the art withthe benefit of this disclosure. Each micro-mirror (also referred toherein as “mirror,” “mirror element,” and “micro-mirror element”) can berotatable (tiltable) on an axis (see, e.g., axis 314) and each mirror inthe array (or a subset thereof) can be mechanically coupled by acoupling element, as further described below. In some embodiments, MEMSactuators may cause the mirrors to rotate and the mechanically coupled,coupling element may force the mirrors to maintain synchronization. Forexample, small differences in mirror mass/dimensions or actuator controltolerances can be mitigated (e.g., reduced or eliminated) by a “bruteforce” approach by way of the mechanical coupling elements. In otherembodiments, the mirrors may be rotated solely by way of a movement ofthe coupling elements. For example, the coupling elements of FIGS. 5A-6Bmay be controlled by a MEMS actuator(s) (e.g., by an actuator configuredat pivot 565 on coupling element support 560, as further describedbelow), which may solely control the rotation of each mirror in themirror array. Alternatively or additionally, some embodiments mayincorporate both control schemes (e.g., utilizing individual mirroractuators and controlling a coupling element). Put simply, some systemconfigurations may include (1) coupling elements (and correspondingcoupling element actuators) configured to mechanically rectify/maintainsynchronization between mirror elements by supplementing actuators thatcontrol the rotation of the mirror elements themselves; or (2) thecoupling elements (and their actuators) may control mirror arrayrotation in lieu of the mirror actuators. Although the following images(FIGS. 5A-8B) may show mirrors, coupling elements, support frames, etc.,having particular dimensions, it should be understood that otherdimensions are possible including wider and/or longer mirrors,differently shaped mirrors, support structures, coupling elements, orany other structure shown throughout this disclosure. In someembodiments, for example, each of the plurality of mirror elements canbe of the same size, dimensions, and/or mass. Although the mirrorelements can be any shape, some embodiments may employ rectangularmirror elements with two opposing ends separated by a first distancedefining a length and longitudinal arrangement of the correspondingmirror element and two opposing sides separated by a second distancedefining a width of the corresponding mirror element, as shown in FIG.3. One of ordinary skill in the art with the benefit of this disclosurewould appreciate the many variations, modifications, and alternativelyembodiments that are possible. To assist the reader in understanding thefigure annotation convention, FIGS. 5A-8 use Arabic numerals (e.g., 1,2, . . . n) to identify each mirror in the arrays, and the figures mayincorporate the numerals to uniquely identify particular elements. Forinstance, axis 536(1) and axis 536(2) can correspond to the axes inmirrors 1 and 2, respectively. It should be noted that although theembodiment shown and described herein generally apply to vehicles, itshould be understood that said techniques may also apply in applicationsand disciplines, including medical diagnostic devices (e.g., anendoscope using a mirror array to redirect light), land surveying, andmore.

Referring to FIG. 5A, only two mirrors of the first type of coupled,synchronous linear array of micro-mirrors 500 in a MEMS system is shown,although any number of mirrors can be employed. For instance, FIG. 3shows 4 mirrors in a linear array, FIG. 4 shows 3 mirrors in a lineararray, and FIGS. 5B-D show six mirrors in a linear array. More or fewermirrors can be used, as well as multiple linear arrays of mirrors.Although the mirrors shown herein rotate along a single axis (e.g., axis536), it should be understood that some embodiments may incorporatemirrors with two axes or rotation across a one or two dimensional array.The techniques and structures described herein may be applied in dualaxle embodiments, as would be appreciated by one of ordinary skill inthe art with the benefit of this disclosure.

In FIG. 5A, micro-mirror array 500 can include a support frame 510 and aplurality of mirror elements 520 disposed in a linear array in anend-to-end, longitudinally configured arrangement within the supportframe. The plurality of mirror elements are defined by a length L andwidth W, where the longitudinal arrangement corresponds to mirrorelements linearly aligned along line 501, as shown. The plurality ofelements in FIG. 5A include a first mirror element 520(1) and a secondmirror element 520(2), where the second mirror element is adjacent toand linearly aligned with the first mirror element 520(1) (e.g.,co-linear with line 501). Each of the plurality of mirror element 520can be rotatable on a rotational axis 536 that is perpendicular to aline (e.g., line 501) defined by the linear array of the plurality ofmirror elements. For example, rotational axis 536 for each mirrorelement can be parallel with the line defining the width W. In somecases, the rotational axis 536 of each mirror element can bisect thecorresponding mirror element into a first portion 524 and a secondportion 522 (e.g., or the right half and left half of mirror 520,respectively, as shown). In some embodiments, one or more couplingelements may be used to mechanically attach some or all of the pluralityof mirror elements together to facilitate a mechanically inducedsynchronized rotation of the plurality of mirror elements. In suchcases, the coupling elements may be driven by an actuator that causesthe coupling element to rotate on a pivot point 565 on a couplingelement support 560 that also defines the axis of rotation 562 for thecoupling element. In other words, support frame 510 may include asupport structure 560 that is configured perpendicular to the lineararray (perpendicular to line 501 and parallel to axis 536) and at alocation between the first and second mirrors, where the supportstructure 560 supports the coupling element 530 at a pivot point 565,and where the coupling element 530 rotates at the pivot point 565. Anaxle, hinge, or other mechanical and/or electromechanical element can beused to rotate the mirror elements on rotational axis 536. Alternativelyor additionally, one or more actuators (controlled by one or moreprocessors of a LiDAR system, as described above) may cause the mirrorto be rotated.

In FIG. 5A, coupling element 530 can have a proximate end coupled to afirst portion 524(1) of the first mirror element 520(1) at a firstcoupling location 534(1) and a distal end coupled to a second portion522(2) of the second mirror element 520(2) at a second coupling location532(2), whereby the coupling element physically couples the first andsecond mirror elements such that a rotation of the first mirror elementcauses a synchronous and equal rotation of the second mirror element,and a rotation of the second mirror element causes a synchronous andequal rotation of the first mirror element. It follows that additionalmirror elements can be included in the array, as described above. In thecase of a third mirror element being added to array 500, the thirdmirror element may be configured adjacent to and linearly aligned withthe second mirror element (e.g., referring to FIG. 5A, to the right ofand in line with mirror 520(2)). A second couple element can beincorporated to mechanically and physically link the third mirrorelement to the first and second mirror elements. The second couplingelement may have a distal end coupled to a first portion 524(2) of thesecond mirror element 520(2) at a first coupling location 534(2), and aproximal end coupled to a second portion 522(3) of the third mirrorelement 520(3) at a second coupling location 532(3), whereby thecoupling element physically couples the second and third mirror elementssuch that a rotation of the third mirror element causes a synchronousand equal rotation of the first and second mirror elements. More mirrorelements N and corresponding coupling elements M can be added in asimilar manner, as would be appreciated by one of ordinary skill in theart with the benefit of this disclosure.

The first and second coupling locations 532, 534 for mirror element520(1) (as well as the other mirror elements in the array) can beconfigured to be equidistant from and on opposite sides of rotationalaxis 536(1). For example, both first and second coupling locations canbe equal distances 552 and 554 from rotational axis 536. By way ofexample, the micro mirrors may be approximately 1 mm in length with thecoupling locations being approximately 0.2 mm (in opposite directions)from rotational axis 536, although other locations are possible (e.g.,0.1 mm, 0.3 mm, etc.). Equidistant coupling locations can helpsynchronize the rotation of multiple mirror elements in the array.Non-equidistant coupling locations on any mirror in the array may causethat mirror to rotate at a different, non-synchronous rate and amount,as would be appreciated by one of ordinary skill in the art with thebenefit of this disclosure.

In some cases, the coupling locations may provide pivot/rotation pointfor the coupling element. For example, as shown in FIGS. 5B-5D, thecoupling element rotates in position at the coupling locations. The axisof rotation for the coupling elements can be configured perpendicular torotational axis 536 of the corresponding mirror element. Supportstructure 510 may include coupling element support 560 that supports thecoupling elements 530 at a pivot point 565. Support structure 510 may beconfigured along axis 562 and the coupling element may rotate on thisaxis. Support structure 510 is shown as a lattice or trellis typestructure, however support structure 510 can be configured in anysuitable manner such that the array of micro-mirrors 520 can be disposedwithin it and operated over an unobstructed range of motion (e.g., seesurface 308 of FIG. 3). One or more actuators may be disposed at pivotpoint 565 to control the rotation of the coupling element at any of oneor more of the mirror elements in the array. In some cases, the range ofmotion for each mirror can be up to 180 degrees. Some embodiments mayutilize ranges of motion closer to 90 degrees, although other suitableranges of motion are possible. Likewise, the range of motion for thecoupling elements at the coupling locations may range anywhere fromapproximately 45-90 degrees, also ranges larger or smaller are possible.In some implementations, the range of motion (i.e., rotational range ofeach mirror element on its corresponding rotation axis) may beinfluenced, in part, by the dimensions of the coupling element inrelation to the mirror element, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure.

In some embodiments, support hinges 539(1) and 539(2) can couple theircorresponding mirror elements to support frame 510. The support hingesmay be configured along the corresponding rotational axis for the mirrorelement they are coupled to and may facilitate the rotation of the firstand second mirror elements along the rotation axis. The support hingescan be flexible (e.g., a torsional bar) that can be deformed as themirror elements rotate. In some cases, the support hinges, the supportframe, the mirror elements, and the coupling elements can be acontinuous, unitary structure with a common substrate (e.g.,semiconductor substrate). For example, the said structures may be formed(e.g., etched, photolithography, etc.) via a semiconductor fabricationprocess and may be one unitary structure formed on a common plane, asshown for example in FIGS. 5A, 5E-F, 7A, and 7E. Typical dimensions areshown in FIGS. 5B-5D (millimeter range), but other dimensions arepossible.

Channels 532, 534 can be formed in the mirror to allow the couplingelement to pivot above and below the mirror element during operation(e.g., mirror rotation/tilting). In other words, the channel can beconfigured to allow the coupling element to pass through as the firstand second mirror elements are rotated. Although a straight channel isshown, any suitable shape or dimension can be used that provides anunimpeded pathway for the coupling element as a corresponding mirrorelement is rotated. Coupling elements may be coupled to mirror elementsin any suitable manner (e.g., micro-hinges, integrated with the mirrorelement, etc.). As shown in FIG. 5A, coupling element 530 can be part ofthe unitary structure as described above.

As described above, a MEMS apparatus can include a number of actuatorsto rotate/orient the individual micro-mirrors in the array, to controlthe coupling element(s) (e.g., rotating control elements at pivot point565 on coupling element support 560), or both. In some cases, one ormore processors may be coupled to (from an external computing device) orintegrated (e.g., fabricated on the same common semiconductor substrate)with mirror assembly 300. The one or more processors can be configuredto control the MEMS actuators (also referred to as “motors” or“micro-motors”) that can be configured to drive the rotation themicro-mirrors at their rotational axis (e.g., at or near 538A), to driveeach coupling element that causes the plurality of mirror elements tosynchronously and equally rotate over a range of motion, or both. FIGS.5B-5D illustrate how, in some embodiments, the micro-mirror arrayoperates as the mirrors are rotated over a range of motion in asynchronous fashion, as described above.

FIG. 5E shows an example of a unitary mirror element with integratedcoupling elements and hinge structures. These structures can beconfigured on a same plane (as shown), or different planes. The mannerin which the hinge structures and coupling elements can flex are shown,for example, in callout box A and B, respectively. Callout box B showshow the coupling element can rotate on a coupling element supportstructure (“coupling element support”), as further described below. Insuch cases, the coupling element support may also be part of the unitarystructure and fabricated in the same manner. FIG. 5F shows anotherembodiments of a mirror structure with a different method of forming thecoupling elements. The callout box and arrows in FIG. 5F show how thecoupling elements and hinge supports may rotate and flex when the mirrorelements are rotating.

FIGS. 6A-6B show simplified functional diagrams of the coupled,synchronous linear array of micro-mirrors shown in FIGS. 5A-5C,according to certain embodiments. Particularly, FIG. 6A shows the mirrorelements synchronously rotated at a first deflection angle (e.g.,positive deflection of approximately 45 degrees), and FIG. 6B shows themirror elements synchronously rotated at a second deflection angle(e.g., negative deflection of approximately (−) 45 degrees). In FIG. 6A,as mirror 520(1) rotates to the first deflection angle, coupling element530 causes the other mirrors in the array to rotate equally andsynchronously, as described above. That is, each mirror 520 can rotateon its corresponding axis 536. Each coupling element 530 can couple toeach mirror 520 at a coupling location (532, 534) that, for each mirror,is typically equidistant from the axis of rotation 536 for that mirror.The coupling element may rotate on an axis 562 at a pivot point 565 thatmay be supported, for example, by a coupling element support 560. One ormore (integrated) MEMS actuators may be configured on axis 536 to rotatethe mirror element, at pivot point 565 to rotate the coupling element,or any combination thereof. In some cases, a subset of the mirrors(e.g., less than that total number of mirrors in the array) may haveactuators or active actuators configured to rotate the mirrors. Incertain embodiments, a subset (e.g., less than that total number ofcoupling elements in the array) of the coupling elements (e.g., lessthan that total number of coupling elements in the array) may haveactuators or active actuators configured to rotate the couplingelements. Although the range of motion (e.g., range of rotation ofmirrors and coupling elements) is shown to be about 90 degrees in total(e.g., +/−45 degrees), other ranges are possible, as would beappreciated by one of ordinary skill in the art with the benefit of thisdisclosure.

FIGS. 7A-7D show a second type of coupled, synchronous linear array ofmicro-mirrors 700 in a MEMS system, according to certain embodiments.Micro-mirror array 700 can be integrated in a larger MEMS structure,such as in the mirror assembly 300 of FIG. 3, in which case micro-mirrorarray 500 can correspond to array 302. Rather than having an array ofcoupling elements that individually couple successive pair of mirrorstogether in the manner described above with respect to FIGS. 5A-6B,certain embodiments of FIGS. 7A-8B employ a single coupling elementacross multiple mirror element that operate in a manner that isanalogous to window blinds with a plurality of louvers where actuating asingle rod can change the orientation of all of the louvers in the set(e.g., from a closed to an open position).

Referring to FIG. 7A, only two mirrors of the first type of coupled,synchronous linear array of micro-mirrors 500 in a MEMS system is shown,although any number of mirrors can be employed. More or fewer mirrorscan be used, as well as multiple linear arrays of mirrors. Although themirrors shown herein rotate along a single axis (e.g., axis 736), itshould be understood that some embodiments may incorporate mirrors withtwo axes or rotation across a one or two dimensional array. Thetechniques and structures described herein may be applied in dual axleembodiments, as would be appreciated by one of ordinary skill in the artwith the benefit of this disclosure.

In FIG. 7A, micro-mirror array 700 can include a support frame 710 and aplurality of mirror elements 720 disposed in a linear array in anend-to-end, longitudinally configured arrangement within the supportframe. The plurality of mirror elements are defined by a length L andwidth W, where the longitudinal arrangement corresponds to mirrorelements linearly aligned along line 701, as shown. The plurality ofelements in FIG. 7A include a first mirror element 720(1) and a secondmirror element 720(2), where the second mirror element is adjacent toand linearly aligned with the first mirror element 720(1) (e.g.,co-linear with line 501). Each of the plurality of mirror elements 720can be rotatable on a rotational axis 736 that is perpendicular to aline (e.g., line 701) defined by the linear array of the plurality ofmirror elements. For example, rotational axis 736 for each mirrorelement can be parallel with the line defining the width W. In somecases, the rotational axis 736 of each mirror element can bisect thecorresponding mirror element into a first portion and a second portion,similar to the embodiments of FIGS. 5A-6B. Alternatively, a differentrotational axis 736(b) may be configured closer to an edge, as shown inFIGS. 7B-D. In some embodiments, a coupling element may be used tomechanically attach some or all of the plurality of mirror elementstogether to facilitate a mechanically induced synchronized rotation ofthe plurality of mirror elements. In such cases, the coupling elementmay be driven by an actuator that causes the coupling element to rotate.Alternatively or additionally, the coupling element may not be driven byan actuator and the rotation of one or more mirrors by one or moreactuators for the mirrors (e.g. 738A) may indirectly cause the couplingelement to rotate, and due to its fixed and rotatable mechanicalcoupling with each of the mirror elements in the array (or a subsetthereof), the other mirrors will equally and synchronously rotate inkind.

In FIG. 7A, coupling element 730 can be coupled to each of the mirrorelements at a coupling location 732. The coupling location for eachmirror element may be located at a same location such that, e.g., thecoupling location 732(1) for mirror element 720(1) is the same distancefrom the mirror element axis of rotation 736(1) or 736(1)(B) as thecoupling location 732(2) from mirror element 720(2) is from axis ofrotation 736(2) or 736(2)(B). By way of example, the micro mirrors maybe approximately 1 mm in length with the coupling locations beingapproximately 0.2 mm from rotational axis 536 or 0.6 mm from rotationalaxis 736(B).

In some cases, the coupling locations may provide pivot/rotation pointfor the coupling element. For example, as shown in FIGS. 7B-7D, thecoupling element rotates in position at the coupling locations on anaxis 762. The axis of rotation for the coupling element can beconfigured perpendicular to rotational axis 736 (or 736(b)) of thecorresponding mirror element. Support structure 710 is shown as alattice or trellis type structure, however support structure 710 can beconfigured in any suitable manner such that the array of micro-mirrors720 can be disposed within it and operated over an unobstructed range ofmotion (e.g., see surface 308 of FIG. 3). In some cases, the range ofmotion for each mirror can be up to 180 degrees. Some embodiments mayutilize ranges of motion closer to 90 degrees, although other suitableranges of motion are possible. Likewise, the range of motion for thecoupling elements at the coupling locations may range anywhere fromapproximately 45-90 degrees, also ranges larger or smaller are possible.In some implementations, the range of motion (i.e., rotational range ofeach mirror element on its corresponding rotation axis) may beinfluenced, in part, by the dimensions of the coupling element inrelation to the mirror element, as would be appreciated by one ofordinary skill in the art with the benefit of this disclosure.

In some embodiments, support hinges can couple their correspondingmirror elements to support frame 710, as described above with respect toFIG. 5A. The support hinges may be configured along the correspondingrotational axis for the mirror element they are coupled to and mayfacilitate the rotation of the first and second mirror elements alongthe rotation axis. The support hinges can be flexible (e.g., a torsionalbar) that can be deformed as the mirror elements rotate. In some cases,the support hinges, the support frame, the mirror elements, and thecoupling elements can be a continuous, unitary structure with a commonsubstrate (e.g., semiconductor substrate). For example, the saidstructures may be formed (e.g., etched, photolithography, etc.) via asemiconductor fabrication process and may be one unitary structureformed on a common plane, as shown for example in FIGS. 5A, 5E-F, 7A,and 7E. Typical dimensions are shown in FIGS. 5B-5D (millimeter range),but other dimensions are possible.

As described above, a MEMS apparatus can include a number of actuatorsto rotate/orient the individual micro-mirrors in the array, to controlthe coupling element, or both. In some cases, one or more processors maybe coupled to (from an external computing device) or integrated (e.g.,fabricated on the same common semiconductor substrate) with mirrorassembly 300. The one or more processors can be configured to controlthe MEMS actuators (also referred to as “motors” or “micro-motors”) thatcan be configured to drive the rotation the micro-mirrors at theirrotational axis (e.g., at 731(1, 2)), to drive the coupling element(730) that causes the plurality of mirror elements to synchronously andequally rotate over a range of motion, or both. FIGS. 7B-7D illustratehow, in some embodiments, the micro-mirror array operates as the mirrorsare rotated over a range of motion in a synchronous fashion, asdescribed above.

FIG. 7E shows an example of a plurality of mirror elements 790(1, 2)with integrated coupling element 794 coupled to each correspondingmirror element at 793(1, 2)and hinge structures (791(1,2) and 792(1,2))configured as a unitary structure. These structures can be configured ona same plane (as shown), or different planes. The manner in which thehinge structures and coupling elements can flex can be similar to theexample shown in FIGS. 5E-F. The rotational axis shown in FIG. 7E may bein the center of the mirror element (bisecting the mirror element) or toone side (shown in broken lines 795), as presented in FIGS. 7B-7D. Someembodiments may have a trench for the hinge structure so that the hingeand coupling element 794 do not come in contact, particularly if thestructures are on the same plane (e.g., such as in the unitarystructures etched from the same substrate, as described above).

FIGS. 8A-8B show simplified functional diagrams of the coupled,synchronous linear array of micro-mirrors shown in FIGS. 7A-7C,according to certain embodiments. Particularly, FIG. 8A shows the mirrorelements synchronously rotated at a first deflection angle (e.g., zerodeflection), and FIG. 8B shows the mirror elements synchronously rotatedat a second deflection angle (e.g., positive deflection of approximately+45 degrees). In FIG. 8B, as mirror 720(1) rotates from the firstdeflection angle to the second deflection angle, coupling element 730causes the other mirrors in the array to rotate equally andsynchronously, as described above. That is, each mirror 720 can rotateon its corresponding axis 736. The coupling element 730 can couple toeach mirror 720 at a coupling location (732) that, for each mirror, maybe equidistant from the axis of rotation 736 (or 736(b)) for thatmirror. The coupling element may rotate on an axis 762 at couplinglocation 732. One or more (integrated) MEMS actuators may be configuredon axis 736 to rotate the mirror element, at coupling location 732 torotate the coupling element on axis 762, or any combination thereof. Insome cases, a subset of the mirrors (e.g., less than that total numberof mirrors in the array) may have actuators or active actuatorsconfigured to rotate the mirrors. Although the range of motion (e.g.,range of rotation of mirrors and coupling elements) is shown to be about90 degrees in total over FIGS. 7B-D, other ranges are possible, as wouldbe appreciated by one of ordinary skill in the art with the benefit ofthis disclosure.

Other variations of the systems, apparatuses, and techniques are withinthe spirit of the present disclosure. Thus, while the disclosedtechniques are susceptible to various modifications and alternativeconstructions, certain illustrated embodiments thereof are shown in thedrawings and have been described above in detail. It should beunderstood, however, that there is no intention to limit the disclosureto the specific form or forms disclosed, but on the contrary, theintention is to cover all modifications, alternative constructions andequivalents falling within the spirit and scope of the disclosure, asdefined in the appended claims. For instance, any of the embodiments,alternative embodiments, etc., and the concepts thereof may be appliedto any other embodiments described and/or within the spirit and scope ofthe disclosure.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosed embodiments (especially in thecontext of the following claims) are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. The term“connected” is to be construed as partly or wholly contained within,attached to, or joined together, even if there is something intervening.The phrase “based on” should be understood to be open-ended, and notlimiting in any way, and is intended to be interpreted or otherwise readas “based at least in part on,” where appropriate. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the disclosure and does not pose a limitationon the scope of the disclosure unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the disclosure.

Numerous specific details are set forth herein to provide a thoroughunderstanding of the claimed subject matter. However, those skilled inthe art will understand that the claimed subject matter may be practicedwithout these specific details. In other instances, methods,apparatuses, or systems that would be known by one of ordinary skillhave not been described in detail so as not to obscure claimed subjectmatter. The various embodiments illustrated and described are providedmerely as examples to illustrate various features of the claims.However, features shown and described with respect to any givenembodiment are not necessarily limited to the associated embodiment andmay be used or combined with other embodiments that are shown anddescribed. Further, the claims are not intended to be limited by any oneexample embodiment.

While the present subject matter has been described in detail withrespect to specific embodiments thereof, it will be appreciated thatthose skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, it should be understoodthat the present disclosure has been presented for purposes of examplerather than limitation, and does not preclude inclusion of suchmodifications, variations, and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the art.Indeed, the methods and systems described herein may be embodied in avariety of other forms; furthermore, various omissions, substitutionsand changes in the form of the methods and systems described herein maybe made without departing from the spirit of the present disclosure. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thepresent disclosure.

Although the present disclosure provides certain example embodiments andapplications, other embodiments that are apparent to those of ordinaryskill in the art, including embodiments which do not provide all of thefeatures and advantages set forth herein, are also within the scope ofthis disclosure. Accordingly, the scope of the present disclosure isintended to be defined only by reference to the appended claims.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain examples include, while otherexamples do not include, certain features, elements, and/or steps. Thus,such conditional language is not generally intended to imply thatfeatures, elements and/or steps are in any way required for one or moreexamples or that one or more examples necessarily include logic fordeciding, with or without author input or prompting, whether thesefeatures, elements and/or steps are included or are to be performed inany particular example.

The terms “comprising,” “including,” “having,” and the like aresynonymous and are used inclusively, in an open-ended fashion, and donot exclude additional elements, features, acts, operations, and soforth. Also, the term “or” is used in its inclusive sense (and not inits exclusive sense) so that when used, for example, to connect a listof elements, the term “or” means one, some, or all of the elements inthe list. The use of “adapted to” or “configured to” herein is meant asopen and inclusive language that does not foreclose devices adapted toor configured to perform additional tasks or steps. Additionally, theuse of “based on” is meant to be open and inclusive, in that a process,step, calculation, or other action “based on” one or more recitedconditions or values may, in practice, be based on additional conditionsor values beyond those recited. Similarly, the use of “based at least inpart on” is meant to be open and inclusive, in that a process, step,calculation, or other action “based at least in part on” one or morerecited conditions or values may, in practice, be based on additionalconditions or values beyond those recited. Headings, lists, andnumbering included herein are for ease of explanation only and are notmeant to be limiting.

The various features and processes described above may be usedindependently of one another, or may be combined in various ways. Allpossible combinations and sub-combinations are intended to fall withinthe scope of the present disclosure. In addition, certain method orprocess blocks may be omitted in some embodiments. The methods andprocesses described herein are also not limited to any particularsequence, and the blocks or states relating thereto can be performed inother sequences that are appropriate. For example, described blocks orstates may be performed in an order other than that specificallydisclosed, or multiple blocks or states may be combined in a singleblock or state. The example blocks or states may be performed in serial,in parallel, or in some other manner. Blocks or states may be added toor removed from the disclosed examples. Similarly, the example systemsand components described herein may be configured differently thandescribed. For example, elements may be added to, removed from, orrearranged compared to the disclosed examples.

What is claimed is:
 1. A micro-electro-mechanical system (MEMS)apparatus configured to redirect light in a light detection and ranging(LiDAR) system, the MEMS apparatus comprising: a support frame; aplurality of mirror elements disposed in a linear array in anend-to-end, longitudinally configured arrangement within the supportframe, the plurality of mirror elements including: a first mirrorelement; and a second mirror element, the second mirror element adjacentto and linearly aligned with the first mirror element; wherein eachmirror element of the plurality of mirror elements is rotatable on arotational axis that is perpendicular to a line defined by the lineararray of the plurality of mirror elements, the rotational axis of eachmirror element bisecting the corresponding mirror element into a firstportion and a second portion; and a coupling element having a distal endcoupled to a first portion of the first mirror element and a proximalend coupled to a second portion of the second mirror element, wherebythe coupling element physically couples the first and second mirrorelements such that a rotation of the first mirror element causes asynchronous and equal rotation of the second mirror element, and arotation of the second mirror element causes a synchronous and equalrotation of the first mirror element.
 2. The MEMS apparatus of claim 1wherein each mirror element includes a first coupling location on itsfirst portion and a second coupling location on its second portion, thefirst coupling location and second coupling location defining where thecoupling element is configured to couple to, wherein the first couplinglocation and the second coupling location are equidistant from and onopposite sides of a rotational axis of the corresponding mirror element.3. The MEMS apparatus of claim 1 further comprising: one or moreprocessors; and one or more MEMS motors controlled by the one or moreprocessors and configured to rotate at least one of the first mirrorelement and second mirror element, wherein the coupling element causesthe plurality of mirror elements to synchronously, mechanically, andequally rotate over a range of motion as the one or more MEMS motorsrotates the at least one of the first mirror element and second mirrorelement.
 4. The MEMS apparatus of claim 3 wherein the range of motionincludes a rotational range of within 90 degrees.
 5. The MEMS apparatusof claim 1 wherein the support frame, the plurality of mirror elements,and the coupling element together form a continuous, unitary structureformed on a common substrate.
 6. The MEMS apparatus of claim 1 furthercomprising: a third mirror element, the third mirror element adjacent toand linearly aligned with the second mirror element; and a secondcoupling element having a distal end coupled to a first portion of thesecond mirror element and a proximal end coupled to a second portion ofthe third mirror element, whereby the coupling element physicallycouples the second and third mirror elements such that a rotation of thethird mirror element causes a synchronous and equal rotation of thefirst and second mirror elements.
 7. The MEMS apparatus of claim 1wherein the first portion of the first mirror element and the secondportion of the second mirror both include a longitudinally-orientedchannel that is configured to allow the coupling element to pass througha plane defined by the first mirror element and the second mirrorelement as the first and second mirror elements are rotated.
 8. The MEMSapparatus of claim 1 wherein the coupling element flexes as the firstand second mirror elements are rotated.
 9. The MEMS apparatus of claim 1wherein the support frame includes a coupling element support configuredparallel to the rotational axes of the first and second mirror elementsand between the first and second mirror elements, and wherein thecoupling element pivots on the coupling element support as the first andsecond mirror elements are rotated.
 10. The MEMS apparatus of claim 1wherein the first mirror element is coupled to the support frame by atleast one support hinge configured along the rotational axis andfacilitates the rotation of the first and second mirror elements alongthe rotational axis.
 11. The MEMS apparatus of claim 10 wherein the atleast one support hinge, the support frame, the first and second mirrorelements, and the coupling element are a continuous, unitary structure.12. The MEMS apparatus of claim 1 wherein each of the plurality ofmirror elements are of the same size and dimensions.
 13. The MEMSapparatus of claim 12 wherein each of the plurality of mirror elementsare rectangular with: two opposing ends separated by a first distancedefining a length and longitudinal arrangement of the correspondingmirror element; and two opposing sides separated by a second distancedefining a width of the corresponding mirror element.
 14. The MEMSapparatus of claim 1 wherein support frame includes a support structurethat is configured perpendicular to the linear array and at a locationbetween the first and second mirrors, wherein the support structuresupports the coupling element at a pivot point, and wherein the couplingelement rotates at the pivot point.
 15. A MEMS apparatus configured toredirect light in a LiDAR system, the MEMS apparatus comprising: asupport frame; a first mirror element coupled to the support frame by afirst support hinge, wherein the first mirror element is rotatablerelative to the support frame along a rotational axis at the firstsupport hinge and defined by an orientation of the first support hinge;a second mirror element coupled to the support frame by a second supporthinge, wherein the second mirror element is rotatable relative to thesupport frame along a rotational axis at the second support hinge anddefined by an orientation of the second support hinge; and a couplingelement coupling the first mirror element to the second mirror elementsuch that a rotation of the first mirror element causes the secondmirror element to rotate synchronously and equally with the first mirrorelement, and a rotation of the second mirror element causes the firstmirror element to rotate synchronously and equally with the secondmirror element.
 16. The MEMS apparatus of claim 15 wherein the first andsecond mirror elements disposed in a linear array in an end-to-end,longitudinally configured arrangement within the support frame.
 17. TheMEMS apparatus of claim 15 wherein the first and second mirror elementshave a rotation range of within 90 degrees.
 18. The MEMS apparatus ofclaim 15 wherein the support frame, the first and second mirrorelements, and the coupling element together form a continuous, unitarystructure formed on a common substrate.
 19. The MEMS apparatus of claim15 wherein the coupling element flexes as the first and second mirrorelements are rotated.
 20. The MEMS apparatus of claim 15 wherein thesupport frame includes a coupling element support configured parallel tothe rotational axes of the first and second mirror elements and betweenthe first and second mirror elements, and wherein the coupling elementpivots on the coupling element support as the first and second mirrorelements are rotated.